1) Field of the Invention
The invention herein relates to a kind of asphalt-grade carbon fiber paper and its process, where the paper comprises primarily of asphalt-grade carbon fiber and paper base material. By the asphalt-grade fiber, as used herein, is meant a carbon fiber obtained from carbonization of asphalt. Through the established procedure of cutting, beating, stirring, paper machine, and drying, asphalt-grade carbon fibers and paper base material of fixed mixing ratio are fully and homogeneously blended into one body and form a kind of asphalt-grade carbon fiber paper which incorporates the conductive, antistatic and shielding actions of asphalt-grade carbon fiber and thereby possesses conductive and statitic elimination effect. Furthermore, such paper can be processed into other electric conductive, thermal conductive and packing products.
2) Description of the Prior Art
To prevent the generation and accumulation of statics, charge consuming material is required in the ennvironment. Thus there are a variety of products made of conductive material that can effectively consume electric charges available on the market, of which, a kind of conductive carbon-coated fibers are applied extensively. Such carbon-coated fibers can be made further into all kinds of conductive materials having low resistance. The technology that produces said carbon-coated fiber entails mainly coating a layer of carbon powder on the surface of fibers which are pressed into paper or mixed into a plastic material and made into highly-conductive material. However, given that the carbon powder coated on the surface of fibers is prone to fall off, such deficiency results in products with signficantly compromised conductivity. Furthermore, in order to prevent the carbon powder from falling off, stirring in subsequent processing into conductive material is limited in terms of time and force. Consequently, carbon coating tends to be non-uniformed and affects the quality of the resulting product. In addition, the entire process of carbon coating is also made more complicated.
From the description above, the known techniques of forming and producing conductive carbon-coated fibers have deficiency in practice and room for breakthrough.
The objective of the invention herein is to provide a simply-made and low cost asphalt-grade carbon fiber paper having superior electrical and thermal conductivity and its process.
The asphalt-grade carbon fiber paper provided herein comprises of primarily asphalt-grade carbon fiber and paper base material with the following compositions and mixing ratio:
Asphalt-grade carbon fiber: paper base material=10xcx9c50:50xcx9c90% (by weight), in which, the paper base material consists of cellulose fibers and resin with the following mixing ratio:
Cellulose fibers: resin=80xcx9c85:15xcx9c20% (by weight).
The aforeaid paper base material may be synthetic fiber as well, such as vinylon fiber, polypropylene fiber, polyethylene fiber and acrylic fiber.
The aforesaid cellulose fiber may be wood pulp fiber, cotton pulp fiber and straw pulp fiber, while the resin may be soluble phenolic resin or phenolic butyl nitrile glue.
The aforesaid asphalt-grade carbon fiber ranges 5xcx9c20 xcexcm in diameter and 3xcx9c6 mm in length.
The aforesaid cellulose fiber ranges 5xcx9c20 xcexcm in diameter and 3xcx9c6 mm in length.
The aforesaid synthetic fiber ranges 5xcx9c20 xcexcm in diameter and 3xcx9c6 mm in length.
The asphalt-grade carbon fiber employed in the present invention has conductive, antistatic and shielding actions, and thus is free of the problem of carbon powder falloff when it is applied in conductive paper and enhances substantially the performance of high-conductivity paper (including improved conductivity and service life). Also, given that the carbon fibers may be thoroughly mixed in the pulp and form an even network, the conductive paper formed will show greatly enhanced conductivity.
Products made of the present invention not only have good conductivity and high thermal conversion ratio, they also have the advantages of fast heat conductance and greater radiation effect. In application, products enjoy longer service life and lower cost.
The process of manufacturing asphalt-grade carbon fiber paper provided in the present invention is also extremely simple that comprises the following steps:
(1) Cutting: cellulose fibers or synthetic fibers are cut into shorter fibers of 3xcx9c6 mm;
(2) Beating: Weigh the asphalt-grade carbon fiber and paper base material according to the proportion described above. Pour them into the beater and add in water to bring the pulp concentration to 0.5xcx9c0.8% and proceed with beating to render all carbon fibers and paper base material in dissolved and dispersed state; the beating time usually lasts 2xcx9c4 hours with temperature controlled at 25xcx9c40xc2x0 C.;
(3) Stirring: Add in rosin in an amount that equals to 0.5xcx9c2% of the absolute dry weight of the pulp, and add in polyvinyl alcohol in an amount that equals to 2xcx9c6% of the absolute dry weight of the pulp, and then stir thoroughly to achieve homogenous mix;
(4) Paper machine;
(5) Drying and reeling into finsihed product.
The last two steps of drying and reeling are the same as the customary technique of paper making.
The present invnetion is further depicted with the illustration of embodiments.
EMBODIMENT 1
Weigh 200 kg of asphalt-grade carbon fiber 5 xcexcm in diameter and 3xcx9c6 mm long; weigh 50 kg of prepared soluble phenolic resin; weigh 750 kg of wood pulp fiber 5 xcexcm in diamater. Subsequently, proceed with the following steps:
(1) Cutting: cut the wood pulp fibers into shorter fibers 3-6 mm long.
(2) Beating: pour the weighed carbon fiber, wood pulp fiber and soluble phenolic resin into the beater, add 130 tons of water, and then proceed with 3 hours of beating with temperature controlled at 25xc2x0 C.;
(3) Stirring: add 10 kg of rosin into the aforesaid pulp and add 50 kg of polyvinyl alcohol, then fully stir the mix;
(4) Paper machine;
(5) Drying and reeling (following the customary paper making technique).
The asphalt-grade carbon fiber paper produced thereof is subjected to tests and the following data are obtained:
Resistance: 100 xcexa9 (sample area 200xc3x97400 mm)
Exothermic power: 484 W
Basic applicable voltage: 220V/110V (12V, 24V and 36V may be applied to products of secondary processing)
Paper weight: 120 g/M2 
wherein the soluble phenolic resin is prepared by reacting phenol amide with formaldehyde in the molar ratio of 2 to 1 under the catalysis of sodium hydroxide or base metal hydroxide.
EMBODIMENT 2
Weigh 400 kg of asphalt-grade carbon fiber 5 xcexcm in diameter and 6 mm long and 600 kg of vinylon fiber. The working steps are the same as those described in Embodiment 1. The asphalt-grade carbon fiber paper produced thereof is subjected to tests and the following data are obtained:
Resistance: 65 xcexa9(sample area 200xc3x97400 mm)
Exothermic power: 745 W
Basic applicable voltage: 220V/110V (12V, 24V and 36V may be applied to products of secondary processing)
Paper weight: 120 g/M2.
EMBODIMENT 3
Weigh 300 kg of asphalt-grade carbon fiber, 650 kg of wood pulp fiber and 50 kg of phenolic butyl nitrile glue. The working steps are the same as those described in Embodiment 1. The asphalt-grade carbon fiber paper produced thereof is subjected to tests and the following data are obtained:
Resistance: 98 xcexa9 (sample area 200xc3x97400 mm)
Exothermic power: 494 W
Basic applicable voltage: 220V/110V (12V, 24V and 36V may be applied to products of secondary processing)
Paperweight: 120 g/M2.
In summary, asphalt-grade carbon fiber paper products made with different mixtures show the following technical indicators:
(1) Under normal atmospheric pressure, the applicable temperature is as follows: for the wood pulp based product up to 130xc2x0 C.; for the synthetic fiber based product up to 180xc2x0 C.;
(2) Fiber size=400xcx9c600 mm in diameter (no limit in length);
(3) Resistance=50 xcx9c2,500 xcexa9/20xc3x9710 mm;
(4) Paper weight=50 g/M2xcx9c120 g/M2;
(5) Exothermic power: 0.1xcx9c0.5 W cm2;
(6) Applicable voltage=220V/110V (12V, 24V and 36B may be applied to products of secondary processing).
Products made of asphalt-grade carbon fiber paper in the present invention can be effectively applied in other products that desire antistatic property and electric and thermal conductivity.